Radiotherapy-Induced Mandibular Bone Complications

The mandible is among the bones most frequently affected by irradiation. The most severe post-radiation injury of the mandibleis osteoradionecrosis (ORN). Conflicting data have been reported on theincidence of this complication, its aetiology and management. The incidenceof mandibular ORN in head and neck cancer patients managed with radicalor postoperative irradiation, has varied widely in the literature from0.4% to 56%. The interpretation of data derived from particular series are difficult due to the different scoring methods and classification systems used for the evaluation of post-radiation bone damage.Although ORN occurs typically in the first three years after radiotherapy,patients probably remain at indefinite risk. The diagnosis of ORN is principally based on the clinical picture of chronically exposed bone. Radiologicalsymptoms include decreased bone density with fractures, cortical destructionand loss of spongiosa trabeculation. Numerous factors that may be associatedwith the risk of ORN include treatment-related variables (for example, total radiotherapy dose, biologically effective dose, photon energy,brachytherapy dose rate, combination of external beam irradiation andinterstitial brachytherapy, field size, fraction size, volume of the mandible irradiated with a high dose), patient-related variables (likedeep parodontitis, pre-irradiation bone surgery, bad oral hygiene,alcohol and tobacco abuse, bone inflammation, dental extraction afterradiotherapy) and tumour-related factors (tumour size or stage,proximity of the tumour to bone, anatomic tumour site). Primary managementof post-radiation bone lesions include conservative modalitiessuch as saline irrigations, antibiotics during infectious episodes, topically applied antiseptics, gentle sequestrectomy and removal of visibly loosenedbone elements as well as treatment with hyperbaric oxygen (HBO). Surgeryis reserved for persistent ORN and includes radical resection of the lesion(sequestrectomy, hemimandibulectomy etc.) with reconstruction. In recentyears the introduction of preventive oral hygiene measures and meticulousdental evaluations before and after irradiation, improvement in radiotherapytechniques and the development of reliable diagnostic and therapeuticprocedures have resulted in a decreased incidence of ORN. Nevertheless,given the severe impact of ORN on patient quality of life, research shouldbe continued to further ameliorate this problem.